A subject inspires a mixture of gases containing carbon monoxide and holds his breath for 10minutes. During those 10seconds, alveolar Pco is 0.5mmHg and the CO uptake is 25ml/min. Which of the following is the diffusing capacity of the lung for CO?
High-Yield Explanation
DLCO = amount of CO entering the blood (VCO) divided by paial pressure of CO in the alveoli (PACO) minus the paial pressure of CO in the blood entering the pulmonary capillaries. Except in habitual cigarette smokers, this latter term is close to zero DLCO = VCO / PACO = 25/0.5 = 50 ml/min/mmHg